Asymmetrical Digital Subscriber Lines (ADSL) is an ANSI standard identified as TI.413 issued in 1995 which presents the electrical characteristics of the ADSL signal as it should appear at a network interface. Generally, ADSL is a high-speed communication technology that allows one client modem, such as that at a remote terminal (RT), to be connected to only one central office (CO) modem through one twisted pair telephone line forming a loop. Typically, discrete multi-tone (DMT) modulation is the chosen line code technique standard in a typical ADSL system. Upstream communications, such as from RT to CO, and downstream communications, such as CO to RT, are divided from one another using frequency division multiplexing (FDM) or using echo canceling, allowing the frequency band for upstream communications to be shared with downstream communications thereby increasing the overall data rate over the loop.
Disadvantageously, the ADSL standard allows only one pair of modems (CO and RT) to communicate over the loop at the same time. The CO modem may send a downstream signal while simultaneously receiving an upstream signal from the RT, frame by frame. Similarly, the RT modem may receive the downstream communication from the CO modem and simultaneously send upstream communication signals to the CO modem.
Since the standardization of ADSL communications, there have been introduced varied implementations and customized uses of the ADSL technology, such as disclosed in commonly assigned U.S. Pat. No. 5,479,447 entitled “Method and Apparatus for Adaptive, Variable Bandwidth, High-Speed Data Transmission of a Multi-Carrier Signal over Digital Subscriber Lines, the teachings of this patent included herein by reference.
As technology evolves and the world becomes more connected including providing access to high-speed internet devices, digital TV (DTV), and even high-definition TV (HDTV), increased bandwidth will be required to connect such devices which may be located at a home or small office. Today, a single pair of twisted telephone line does not provide sufficient bandwidth to allow communications at the data rate required for some of these devices, which is about 20 Mbps for HDTV in the case of line conditioning. Although cable modems may be designed to reach up to 40 Mbps, there are many users that are required to share this data bandwidth. This means that the 40 Mbps is the burst data rate for one user, or the maximum data rate for all users.
There is desired a higher bandwidth modem and communication network that provides for a higher data rate access than that provided by conventional ADSL modems operating over a single loop of twisted pair of telephone wire. Such an improved higher data rate communication is desired to be compatible with ADSL standards, and which can support high speed communications suitable for the internet, digital TV, and even HDTV.